Introduction of a ram to anoestrous ewes induces an almost instantaneous rise in LH pulse frequency. This is commonly sufficient to overcome the seasonal suppression of the hypothalamic-pituitary axis and induce a synchronous first ovulation (Martin et al., 1986). A preliminary study at the University of Newcastle upon Tyne identified a significant positive effect of repeated fence-line ram exposure on the synchrony of breeding and lambing in ewes (Hawken et al., 2003). The ram effect is widely accepted to be predominantly mediated through pheromones however previous studies have emphasised the importance of other exteroreceptive cues. Optimal response to the ram effect during anoestrus is obtained when ewes are exposed to the full complement of male sensory signals (Pearce and Oldham, 1988). This study investigated the application of repeated exposure to vasectomised rams during the beginning of the breeding season as a non-pharmacological method of synchronisation of oestrus and lambing in ewes.